Process for the polymerization of ethylene

Claim 1

In a slurry polymerization process for producing an ethylene homopolymer or ethylene-α-olefin copolymer in multiple stages, in which the gas phase hydrogen concentration in each stage is different, by the use of a catalyst system comprising a transition metal compound component and an organoaluminum compound component, the improvement which comprises conducting the polymerization in a molar ratio, of gas phase hydrogen to ethylene, of 0.5 to 15 in the first stage thereby polymerizing 30 to 95% by weight of the overall polymerization amount and in the second stage in a molar ratio, of gas phase hydrogen to ethylene, not exceeding 0.2, by using as the transition metal compound component a solid catalyst component comprising a titanium compound and/or vanadium compound supported on a solid carrier obtained by the reaction of an organomagnesium compound and a halogenated aluminum compound and/or halogenated silicon compound represented by the general formula R'.sub.n AlX.sub.3-n and/or the general formula R.sup.2.sub.m SiX.sub.4-m wherein R' and R 2 are each an alkyl, cycloalkyl, aralkyl, aryl, or alkenyl group having up to 20 carbon atoms, X is a halogen atom, and n and m are numbers defined by 0≦n<3 and 0≦m<4, respectively; wherein the molar ratio of said organomagnesium compound to said halogenated aluminum compound and/or halogenated silicon compound is within the range of 0.1/1 to 10/1; wherein the amount of said titanium compound and/or vanadium compound supported on said solid carrier is 0.1 to 30% by weight in terms of titanium and/or vanadium atom based on the total amount of the supported compound and the carrier; wherein said reaction of the organomagnesium compound with the halogenated aluminum compound and/or halogenated silicon compound is carried out at 0° to 100° C.; and, wherein said organomagnesium compound is represented by the general formulae R.sup.3 MgX and/or R.sub.2.sup.3 Mg wherein R 3 is an alkyl, aralkyl, aryl, or alkenyl group having up to 20 carbon atoms.